1. Field of the Invention
The invention relates to file management and filing technology.
2. Description of the Prior Arts
A new kind of files has come into being in recent years where the conditions such as the period of usage and the number of repetitive usages can be arbitrarily set up by the author, wherein files can no longer be used once their periods of usage are expired.
However, those files that are no longer usable due to expiration of their usage periods are still stored in media such as floppy disks and hard disks as they are not automatically removed. This means that they occupy the medians memory areas forever.
Therefore, it is desirable to have such a file that can be automatically deleted without the user's intervention, or a file that can be automatically deleted leaving only information that is necessary for the user.
Among the files where usage periods or number of repetitive usages are set up, popular ones are the files that contain trial version software used for the promotion of software products for potential customers. This means that it would defeat the purpose of such trial files if the contents of the files can be changed or copied. Therefore, it is desirable to have files that prevent any modification or copying the contents of the files.